Universe Guide

IV Librae

IV Librae Facts

  • IV Librae is a eclipsing giant star that can be located in the constellation of Libra. The description is based on the spectral class.
  • IV Librae is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K1III + (F)) of the star, the star's colour is orange to red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 597.37 light years away from us. Distance

IV Librae's Alternative Names

HIP76480 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD139183.

IV Librae has alternative name(s) :- IV Lib, IV Lib.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD-17 4379.

More details on objects' alternative names can be found at Star Names .

Location of IV Librae

The location of the giant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For IV Librae, the location is 15h 37m 13.37 and -18° 20` 06.1 .

Proper Motion of IV Librae

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving 1.36 ± 0.68 milliarcseconds/year towards the north and 5.94 ± 1.19 milliarcseconds/year east if we saw them in the horizon. . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of IV Librae

IV Librae Temperature and Colour

Based on the star's spectral type of K1III + (F) , IV Librae's colour and type is orange to red giant star. The star has a B-V Colour Index of 0.76 which means the star's temperature is about 5,391 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

IV Librae Radius

IV Librae estimated radius has been calculated as being 4.57 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,177,100.87.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 4.11. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

IV Librae Apparent and Absolute Magnitudes

IV Librae has an apparent magnitude of 8.39 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 1.85 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.08. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to IV Librae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.92 which gave the calculated distance to IV Librae as 662.93 light years away from Earth or 203.25 parsecs. If you want that in miles, it is about 3,897,117,118,644,610.58, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 5.46 which put IV Librae at a distance of 597.37 light years or 183.15 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 37,777,136.03 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

Travel Time to IV Librae

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736544,301,977.81
Speed of Sound (Mach 1)767.269522,119,694.22
Concorde (Mach 2)1,534.54261,059,506.87
New Horizons Probe33,00012,139,583.51
Speed of Light670,616,629.00597.37

Variable Type of IV Librae

The star is a eclipsing Beta Persei (Algol) variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. IV Librae brightness ranges from a magnitude of 9.000 to a magnitude of 8.457 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 6.4 days (variability).

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Additional IV Librae Facts and Figures

Visual Facts

Primary / Proper / Traditional NameIV Librae
Alternative NamesIV Lib, HD 139183, HIP 76480, BD-17 4379, IV Lib
Spectral TypeK1III + (F)
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeGiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude 1.85 / 2.08
Visual / Apparent Magnitude8.39
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)15h 37m 13.37
Declination (Dec.)-18° 20` 06.1
Galactic Latitude29.33 degrees
Galactic Longitude349.04 degrees
1997 Distance from Earth4.92 Parallax (milliarcseconds)
 662.93 Light Years
 203.25 Parsecs
2007 Distance from Earth5.46 Parallax (milliarcseconds)
 597.37 Light Years
 183.15 Parsecs
 37,777,136.03 Astronomical Units
Proper Motion Dec.1.36 ± 0.68 milliarcseconds/year
Proper Motion RA.5.94 ± 1.19 milliarcseconds/year
B-V Index0.76

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassEclipsing
Variable Star TypeBeta Persei (Algol)
Mean Variability Period in Days6.361
Variable Magnitude Range (Brighter - Dimmer)8.457 - 9.000

Estimated Calculated Facts

Radius (x the Sun)4.11
Effective Temperature5,391 Kelvin

Sources and Links

SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
139183-17 4379.0A8.100009.00000-10.00000G0Yellow

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